Notes and Known IssuesThe following issues relate to using iOS SDK 9.0 to develop code.

App StoreNoteiOS 9 enforces the UILaunchImages requirement; apps can no longer declare the same launch image to support different interface orientations.

Known IssueUsers might be prompted twice for credentials on the first In-App Purchase.

Apple IDNotesSome users will be offered to turn on two-factor authentication on their Apple ID. For more information about two-factor authentication see developer.apple.com/support/two-factor-authentication.If you turn on two-factor authentication on your Apple ID, iTunes purchases on Mac and Windows and store purchases on Apple TV will require you to append a six-digit verification code to the end of your password the first time you use that device. The six-digit code will display automatically on your iOS 9 or OS X El Capitan devices, or can be sent to your trusted phone number via a text message or phone call.Apple PayNoteThe format of the postal code that is returned prior to full authorization has changed from iOS 8. In some cases, it may be truncated from what was previously being returned.

AVFoundationNotesThe canUseNetworkResourcesForLiveStreamingWhilePaused property has been added to AVPlayerItem. The default value is NO for apps linked on or after iOS 9.0 or OS X 10.11, but YES for apps that were linked earlier.To minimize power usage, set this property to NO if you do not need playback state to stay up to date while paused.

AVQueuePlayer now supports a mixture of file-based media and HTTP Live Streaming media in its queue. Prior to this, you had to ensure that all items in the queue were of the same type.For apps linked against iOS 9 or later, the media interruption behavior for AV(Queue)Player has changed.Before iOS 9, apps could interrupt other media-playing clients by associating or adding AVPlayerItem to AVPlayer or by modifying the time or date of the current AVPlayerItem (using the seekToTime: or seekToDate: methods). In iOS 9, these operations interrupt only when AVPlayer object’s playback rate is changed to a non-zero value through the rate property or play method.

Picture in Picture playback might stop and the Picture in Picture button might disappear when using AVPlayerViewController for video playback and replacing the underlying AVPlayer object’s current item using replaceCurrentItemWithPlayerItem:.The cancelPictureInPicture method is deprecated.CBCentralManagerNoteThe retrievePeripherals: and retrieveConnectedPeripherals methods were deprecated in iOS 7.0 and removed in iOS 9.0. Apps that use these methods will crash on launch or upon pairing an accessory.

FoundationNotesThere is new Foundation API that can be used to detect if the device is in Low Power Mode. See the updated Energy Efficiency Guide for iOS Apps for details.Horizontal location constraints should consistently reference either left/right or leading/trailing attributes. For apps linked against the iOS 9 SDK, NSLayoutConstraint will throw an exception if you attempt to create a constraint between a leading/trailing attribute and a left/right attribute.iCloud DriveNoteThe fetchAllChanges property on CKFetchRecordChangesOperation has been deprecated, and will be removed in iOS 9.

KeyboardsNoteThe setting to use a third-party keyboard as the default keyboard for text input is not always respected.

KeychainNoteiCloud Keychain will not sync passwords and credit cards with betas of iOS 9 and OS X El Capitan.

MusicNoteWhen users plug in headphones or connect to Bluetooth or CarPlay in their car, their favorite music app appears on the lock screen or the car display.

For your app to be eligible for this, it must publish to Now Playing upon launch and consistently maintain a Now Playing state. A common practice upon launch is to continue playing the track from when the app was last exited.

Known IssueSome tracks you have previously purchased won’t play.

Workaround: Sign out of the Store and then sign back in.

NetworkingNotesWhen negotiating a TLS/SSL connection with Diffie-Hellman key exchange, iOS 9 requires a 1024-bit group or larger. These connections include:Secure Web (HTTPS)Enterprise Wi-Fi (802.1X)Secure e-mail (IMAP, POP, SMTP)Printing servers (IPPS)DHE_RSA cipher suites are now disabled by defaults in Secure Transport for TLS clients. This may cause failure to connect to TLS servers that only support DHE_RSA cipher suites. Applications that explicitly enable cipher suites using SSLSetEnabledCiphers are not affected and will still use DHE_RSA cipher suites if explicitly enabled.Safari may see a “Safari can’t establish a secure connection to the server” error page. Safari and other clients of CFNetwork API (NSURLSession, NSURLConnection, CFHTTPStream, CFSocketStream and Cocoa equivalent) will show “CFNetwork SSLHandshake failed” error in Console.

ReplayKitKnown IssuePlaying a video while ReplayKit recording is ON stops the ongoing recording session and the video fails to play.

Workaround: During restore, change your region to match your language. You can change it back after the restore is over.

SafariNotesWhen Done is tapped in a SFSafariViewController, it is automatically dismissed. You no longer need to dismiss it in the delegate method safariViewControllerDidFinish:.“Find on Page” is now available both from the Share sheet as well as in the Completions List.Request Desktop Site has moved; it’s now in the Share sheet instead of Favorites.Web Browser–to–Native App Handoff does not work with your app if the apple-app-site-association file isn’t correctly formatted and signed. For more information, see Handoff Programming Guide and Shared Web Credentials Reference.Secure TransportNoteDHE_RSA cipher suites are now disabled by default in Secure Transport for TLS clients. This may cause failure to connect to TLS servers that only support DHE_RSA cipher suites. Applications that explicitly enable cipher suites using SSLSetEnabledCiphers are not affected and will still use DHE_RSA cipher suites if explicitly enabled.

UIKitNotesIf initialized with a nil nibName value, UIViewController.nibName has always looked for a nib with a similar name as the view controller’s class, and defaulted to that value if loadView is not overridden.Prior to iOS 9, subclasses of UIViewController that were written in Swift would require that their corresponding nib file name include the module prefix.

To improve flexibility in the event of refactoring, you can omit the module name from the nib filename in code that runs in iOS 9. UIViewController.nibName still prefers a name that contains the module prefix, but falls back to an unqualified name if a nib with the fully-qualified name is not found.

In iOS 9, when layoutIfNeeded is sent to a view and all of the following conditions are satisfied (which is not common), we apply fitting-size constraints (width/height = 0 at UILayoutPriorityFittingSizeLevel) instead of required size constraints (width/height required to match current size):The receiver is not yet in the subtree of a view that hosts a layout engine, such as window, view controller view (unless you have set translatesAutoresizingMaskIntoConstraints to NO on that view—or created constraints that have one item in its subtree and one item outside it), table view cell content view, and so on.The final ancestor (that is, top-level view) of the receiver has translatesAutoresizingMaskIntoConstraints set to NO.The top-level view has a subview that is not a UIViewController-owned layout guide that also has translatesAutoresizingMaskIntoConstraints set to NO.Under condition 1, we create a temporary layout engine from the top-level view and add all the constraints from the subtree to it. The problem is that we need to add some constraints that make the size of the top-level view unambiguous in the layout engine. The old behavior (prior to iOS 9) was that we would add constraints to restrict the size of the top-level view to its current bounds for any situation under condition 1. This really doesn’t make sense when you add conditions 2 and 3 and can result in unsatisfiable-constraints logging and broken layout.So in iOS 9, for this special case only, we use fitting-size constraints instead.

This means that if you are sending layoutIfNeeded to a view under these conditions in iOS 9, you must be sure that either you have sufficient constraints to establish a size for the top-level view (which usually, though not always, is the receiver) or you must add temporary size constraints to the top-level view of layout size you desire before sending layoutIfNeeded, and remove them afterward.

For apps linked on iOS 9 or later, UITextView will now always correctly constrict its NSTextContainer to the fit inside the view when scrolling is disabled. Overflowing lines that lie outside of an NSTextContainer, even partially, are not rendered.In previous iOS releases, the NSTextContainer sometimes was not constricted in size. This meant that logically overflowing lines were erroneously rendered. If you are seeing previously rendered lines at the end of your text view no longer rendered after linking your app against iOS 9, this behavior change is the likely cause. You can remedy this by making your UITextView larger, or perhaps by adjusting the bottom value of the text view’s textContainerInset property.

There is a redesigned UI for printing that includes a print preview (presented from UIPrintInteractionController or UIActivityViewController). For apps that provide printing items or use only built-in UIPrintFormatter objects (such as UISimpleTextPrintFormatter, UIMarkupTextPrintFormatter, UIWebViewPrintFormatter, or the UIViewPrintFormatter of any system-provided view), nothing additional is needed for the print preview to display.Apps that subclass UIPrintPageRenderer or UIPrintFormatter to draw content for printing must be built with the iOS 9 SDK for the preview to display. The behavior of UIPrintPageRenderer has been updated to call drawPageAtIndex:inRect: multiple times with potentially different page sizes and margins. Various methods on UIPrintPageRenderer may be called from a non-main thread, but never from multiple threads concurrently.

UIPickerView and UIDatePicker are now resizable and adaptive—previously, these views would enforce a default size even if you attempted to resize them. These views also now default to a width of 320 points on all devices, instead of to the device width on iPhone.Interfaces that rely on the old enforcement of the default size will likely look wrong when compiled for iOS 9. Any problems encountered can be resolved by fully constraining or sizing picker views to the desired size instead of relying on implicit behavior.

WebkitNoteThe if-domain and unless-domain value strings only match the exact domain. To match the domain and any subdomains, begin the string with the asterisk character (*).